Are you refering to "diesel locomotive cable"? It has a strand construction like that of welding cable, but not as fine. It normally comes in a 2000 volt rating. I have used it a number of times to hook up large motors and generators because of its flexibility. It is expensive, but the labor savings on the terminations will make up for the wire cost on shorter runs. I have also used it on larger DC motors (over 1000hp) because the motors had a 700 volt armature and I couldn't use 600 volt building wire. I think its original use was to connect to the traction motors on locomotives. The fine strand construction was required to avoid breakage due to vibration. It comes in odd sizes, the last I used was 535.3 kcmil.